The invention relates to a holder for a syringe, particularly to a holder to be attached to a syringe which is used for injecting liquid or gel and which has a cylinder barrel of a relatively small diameter and made of glass, and also to an injection device using the holder.
Conventionally, the length and diameter of a syringe are determined in accordance with the amount and kind of liquid or gel to be injected, in a range wherein the syringe can be easily operated.
However, a syringe which is used for injecting a small amount of liquid or gel is short in length in the longitudinal direction thereof and has a small diameter. Therefore, such a syringe hardly fits in the hand and is poor in operability. This defect of the syringe causes a problem when the syringe is used in a case where delicate operations are required, such as in the case of an ophthalmic operation.
Recently, a cylinder barrel which constitutes a syringe is often made of a synthetic resin. Depending on the kind of the charged parenteral solution, however, a cylinder barrel must be made of glass. Many syringes in the form of an ampule into which a predetermined amount of liquid or gel is previously charged (so called as a pre-filled syringe) are recently used. In such a pre-filled syringe, a cylinder barrel made of glass is used in order to prevent the quality of the liquid or gel from being deteriorated during the preservation period.
Unlike a syringe made of a synthetic resin, in a cylinder barrel made of glass, it is difficult to increase the size of a finger holding portion because of restrictions caused by characteristics of glass and a manufacturing process and so on.
When the piston is pressed so as to eject the liquid or gel, therefore, only a part of a finger is held by the finger holding portion, so that stable ejection is hardly conducted. This is noticeable particularly in the case where liquid or gel of high viscosity such as a hyaluronic acid preparation or a solution of hydroxypropyl methylcellulose is used.
To comply with this, as disclosed in, for example, Japanese utility model unexamined publication (Kokai) No. Sho. 57-100935 discloses a structure in which a holder having a flange of a large diameter is fitted onto a cylinder barrel so as to practically increase the size of a finger holding portion.
Since the holder disclosed in the publication is intended only to improve the finger holding portion, the holder has the maximum length which is approximately equal to the width of a finger and is fitted to the basal end of the cylinder barrel, and a stepped portion is formed between the cylinder barrel and the holder. Therefore, the holder has a problem in that a syringe cannot be operated under a stable state in the case such as the holding of the syringe or the insertion of the needle.
On the other hand, a glass cylinder barrel is used while an injection needle is fittingly inserted under a pressure into and supported by a fitting part of a neck portion formed at the tip end of the cylinder barrel. In the case where liquid or gel of high viscosity is to be injected into the object, for example, a high pressure of the liquid or gel is applied to the injection needle. When the press insertion is not sufficient, there is a fear that the applied high pressure may cause the injection needle to slip off.